Machine for extruding polyethylene on wood

ABSTRACT

A machine and process for extruding polyethylene directly around a wooden core such as a broom handle that is moved vertically downward through a plastic extruding die placed close above a water surface of a tank containing cold water to cause a shrinking of the extruded plastic for a tight fit upon the wooden handle as the coated handle descends into the water. Provision is made to keep the wood handle cool during the coating operation and any moisture therein that would effect blistering of the coating.

United States Patent inventors Harold Miller 3235 Emons Ave, Brooklyn, NY. 1 1235; Jack Miller, 2055 Center Ave., Fort Lee, NJ. 07024; Michael Miller, 2055 Center Ave., Fort Lee, NJ. 07024 Appl. No. 792,285 Filed Jan. 21,1969

Patented July 6, 1971 MACHINE FOR EXTRUDING POLYETHYLENE ON WOOD 8 Claims, 13 Drawing Figs.

US. Cl 18/13 Int. Cl 1329i 3/10 Field ol'Search 18/13, 14,1

[56] References Cited UNITED STATES PATENTS 2,205,628 6/1940 Morrison 18/1 2,287,825 6/1942 Postlewaite 25/38 2,339,211 1/1944 Whitehouse 18/1 3,106,748 10/1963 Skobel 18/13 Primary Examiner-J. Spencer Overholser Assistant Examiner-Norman E. Lehrer Attorney-Polachek and Saulsbury ABSTRACT: A machine and process for extruding polyethylene directly around a wooden core such as a broom handle that is moved vertically downward through a plastic extruding die placed close above a water surface of a tank containing cold water to cause a shrinking of the extruded plastic for a tight fit upon the wooden handle as the coated handle descends into the water. Provision is made to keep the wood handle cool during the coating operation and any moisture therein that would effect blistering of the coating.

PATENTEB JUL 6 I971 SHEET 5 UF 6 FIG. IO

in van furs 7r0/d Ml Her:

Jack Mil/er ff" Ic/me/ MI//I" if? ATTURNE 5 PATENTEn'JuL SIS?! 3,590.43]-

' sum 6 OF 6 1 FIG.II

ro/a' Mil/er, Ck Mil/CI; Michael Mil IHVF/ifdlii MACHINE FOR EXTRUDING POLYETI-IYLENE N WOOD This invention relates generally to a machine and process for manufacturing plastic coated articles. More specifically, it relates to machines for producing plastic covered wooden broom handles or the like.

A principal object of the present invention is to provide a machine for the manufacture of broom handles or the like comprised of wooden cores that are coated with polyethylene plastic coverings that will be shrink-fitted upon the cores so to prevent relative twisting movement therebetween during use, such as is evident in conventional plastic coated broom handles which are manufactured by inserting a wooden core into a preformed plastic tube.

Another object of the invention is to provide a machine for the manufacture of plastic coated wooden broom handles or the like directly upon the wooden core.

Another object is to provide a machine for manufacture of plastic coated wooden broom handles or the like, wherein the plastic coating during the molding and shrinking process assumes, on its inner surface, the grained surface of the wooden core, thus forming a nonslip engagement therewith.

Another object of the invention is to provide a machine for the manufacture of plastic coated wooden broom handles or the like, wherein the wooden stick or core may comprise inexpensive inferior grade of wood having imperfections that are hidden by the plastic coating, such as would not be possible if the wooden stick were left unsheathed without a plastic coat.

Another object of the invention is to provide a machine for the manufacture of plastic coated wooden broom handles, wherein the wooden stick may comprise green unseasoned wood, and wherein means are provided in the machine to maintain the wooden stick in a cool condition during the plastic extruding process thereupon, so as to prevent moisture evaporation from the wood and formationof water droplets between the stick and plastic coating which would deform the coating with unsightly blisters resulting from the heat from extruding dies and the expansion of the droplets into steam.

A further object of the invention is to provide a machine for the manufacture of plastic coated wooden broom handles, wherein the entire newly coated broom handle is immediately plunged into cold water after the extrusion process thereupon, thus cooling thehandle to prevent the hot plastic and heated dies from creating moisture from the stick, and at the same time shrinking the plastic on to the wood.

A still further object of the invention is to provide a process for extruding polyethylene plastic directly upon a wooden article.

A still further object of the invention is to provide a machine forthe manufacture of plastic coated wooden broom handles which is simple in design, inexpensive to manufacture, rugged in construction, easy to use, and efiicient in operation.

For a better understanding of the invention, reference may be had to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a side elevation view of a machine for the manufacture of plastic coated wooden broom handles, the machine being shown partly in cross section, a coated broom handle being shown about to be removed from the tank.

FIG. 2 is a top plan view of the die mechanism as viewed from line 2-2 of FIG. 1.

FIG. 3 is a cross-sectional view taken on line 3-3 of FIG. 2.

FIG. 4 is a cross-sectional view taken on line 4-4 of FIG. 2, a fragment of a wooden broom handle being shown preparatory to insertion in the machine.

FIG. 5 is a cross-sectional view taken on line 5-5 of FIG. 2.

FIG. 6 is a cross-sectional view taken on line 6-6 of FIG. 3.

FIG. 7 is a side view of a finished handle manufactured by the machine, the handle being shown partly broken away.

FIG. 8 is a perspective view of the control mechanism for removal of a completed handle from the operational unit of the machine.

FIG. 9 is a fragmentary cross-sectional view showing the junction of adjacent coated sticks after the plastic extrusion process and prior to being broken apart from each other.

FIG. 10 is a view similar to FIG. 9 showing the step of breaking off a finished handle from a handle structure yet under construction.

FIG. 11 is an exploded perspective view of the principal components of the extrusion die.

FIG. 12 is a cross-sectional view taken through the die on line 12-12 of FIG. 4; and

FIG. 13 is a diagrammatic view showing one possible form of stick automatic feeding apparatus to the die parts being shown broken away.

Referring now to the drawing in detail, the reference numeral 10 generally represents a machine for the manufacture of plastic coated wooden broom handles, or the like, according to the present invention, wherein there is an operational unit 11 mounted upon a water tank 12, the unit 11 including an extrusion die mechanism 13 that is connected to a conventional plastic extruding machine 14 that injects molten polyethylene or other plastic material to the extrusion die 13. An associated stick handling apparatus 15 (see FIG. 13) is provided for automatically feeding sticks to the extrusion die mechanism 13.

The stick feeding apparatus I5 may comprise any conventional apparatus that will automatically feed wooden sticks 16, one after another, vertically downward along a singular axis into the die 13. One such apparatus, suggested in FIG. 13, has a hopper I7 having inclined bottom wall 18 for directing sticks 16 into inclined chute l9 from which the sticks are picked up by a circular closure plate 20 at one end with housing 20 hav ing notches 21, each of which receive one stick. The circular plate 20' is connected to a central shaft 22 that is rotationally driven by an electric motor 23 having a motor output shaft 24 carrying a pulley 25 connected by endless belt 26 to a pulley 27 mounted on shaft 22. The sticks are carried in upright position across a platform 28 closing the lower end of housing 20 having a notch 28:: therein through which the sticks are individually dropped one upon another, end to end, so as to descend through a stick feeding mechanism 29 positioned over the extrusion die 13. I

The stick feeding mechanism 29 comprises a part of the operational unit 11 including a vertical tube 30 through which the sticks 16 are vertically moved into the. die 13. Opposite side openings 31 in the tube 30 allow access for grooved feed rollers 32 to engage sticks 16 therebetween and feed the same at a controlled speed to the die 13. The rollers 32 are mounted on shafts 33 and 34.(see FIGS. 3 and 4). Shaft 33 is journaled in a pair of spaced-apart bearing blocks 35 mounted upon an upper plate 36. The other shaft 34 is journaled in a pair of slide blocks 37, each of which is horizontally slidable within slots 38 formed on each of the blocks 35. A back up plate 39 and compression coil spring 39 between the slide block 37 and the outer end of the slot normally urges the slide blocks to move in a direction so that the rollers 32 bear pressure against the sides of the stick 16 and thus assure a press fit thereagainst for regulated feeding speed. Gears 40 on the ends of the shafts 33 and 34 are in toothed engagement with each other so as to transmit positive driving power from each roller to the respective side of the stick. It will be noted that a sufficient play between the teeth of the gears allows for the slight movement sidewardly of the shaft 34 necessary so that the rollers bear pressure against the stick.

A sprocket 41 mounted on shaft 33 is driven by an endless sprocket chain 42 driven by a sprocket 43 on an output shaft 44 of a gear reduction unit 45 (see FIG. I). An electric motor 46 mounted on a bracket secured upon the tank 12 has a motor shaft 47 carrying a pinion 48 connected by endless gear chain 49 with a pinion 50 on an input shaft 51. of the gear reduction unit 45. Thus, the motor 46 powers the feed mechanism 29.

The plate 36 is mounted by means of long bolts 52 in spaced relation above a lower plate 53 and spacers 54 fitted around each bolt. The lower plate 53 has a central restricted opening 55 therethrough, through which the stick 16 is fed. This plate 53 is mounted in spaced relation over the extrusion die 13 by means of bolts 56 fitted through spacers 57 between the plate 53 and the die. The plate 53 is water colled and thus serves as a heat shield to prevent heat from the die 13 being transferred to the portion of the stick extending above the lower plate 53. As shown in FIGS. 4 and 6, a pair of tubular openings 58 and 59 extend parallel horizontally through the plate 53 with the opening 55 being located therebetween. A hose fitting 60 is secured to one end of opening 58 for attachment to a hose 61 connected to a cold water source. Fittings 62 attached to a hose 63 allow passage of the cold water from one tubular opening to the other. The opposite end of opening 59 allows discharge of the water from the plate 53. Circulation of the water cools the heat shield area around the opening 55 of the plate 53.

The extrusion die 13, as shown in FIGS. 4, l1 and 12 is comprised of a hollow block 64 having a central bore into which is fitted a tubular core 65, the core being secured in fixed position to the block 64 by a transverse pin 66 between the block and core. The core 65 includes a central opening 67 downwardly through which the sticks 16 axially pass. The lower end of the core 65 is headed and inwardly tapered to form an outer conical wall 68 adjacent the lower edge of a cylindrical outer wall 69 having outwardly projecting lugs or spacers 70 therearound with spaces 71 therebetween. The block 64 has a cylindrical central opening 72 into which the lugs are fitted, thus seating the core concentrically within opening 72.

A die bottom plate 73 is secured by bolts 74 to the underside of the block 64, the plate 73 having a hub with a conical inner surface 75 on its upper side into which the conical lower end of the core is received in spaced relation so to allow polyethylene or other plastic material to flow therebetween. A central opening 76 through the plate 73 is of a size so as to receive the stick therethrough as well as a thin film or coat 77 of the polyethylene formed directly around the stick. The die 13 is secured by bolts 78 to the output end of the machine 14, the block 64 having a lateral passage 79 communicating between the machine 14 and cylindrical space 80 between the core wall 69 and block opening 72.

The water tank 12 comprises a vessel open at the top and of sufficient depth so as to receive the full length of the broom sticks 16 in upright position therein which move from the die 13 vertically and downwardly into the tank. Cold water 81 is filled into the tank, the level of the water being relatively close to the die 13 so to be immediately effective upon the work as soon as the extrusion is performed.

The operational unit 11 is secured by appropriate brackets to the tank 12. The operational unit 11 includes an automatic mechanism 82 which severs and discards the finished plastic coated handles 108 from the unit and allows them to float upwardly to the surface of the water in the tank where they may be gathered up by a workman 83.

The discard mechanism 82, shown in FIGS. 1, 6 and 8, includes a an bar 84 secured at its upper end to an angular bracket 85 upon the tank edge 86, the bar extending downwardly into the tank water 81. A lever 87 is connected pivotally free by a pin 88 to the lower end of the bar 84. One end of the lever has a platform 89 against which the lower end of a completed handle abuts during its downward travel. The opposite end of the lever 87 is connected pivotally free by a pin 90 to a lower end of a rod 91 extending upwardly through pivotable opening 92 in the bracket 85, the upper end of the rod 91 being in position to activate a microswitch 93 mounted upon the bracket 85. The microswitch is in an electrical circuit with a solenoid 94 which drives a piston 95 within a pneumatic valve cylinder 96. An air intake hose 97 is connected from an air compressor (not shown) to a mid portion of the valve cylinder 96 and hoses 98 and 99 are connected to opposite ends thereof, the piston being movable between opposite ends of the cylinder 96 so as to selectively direct air to either of the hoses 98 or 99. The hoses 98 and 99 are connected to opposite ends of a work cylinder 100 having a piston 101 therebetween to which there is connected a ram 102 extending outward of the cylinder 100. The ram 102 is in position to ram against a pivotable bar 103. This bar 103 comprises a vertical member extending into the tank water, the bar being pivotable at its upper end about a bolt 104 fitted into a block 105 mounted upon the lower plate 53. The bar 103 has a plurality of horizontally extending tines 106 which are positioned so to push sidewardly the lowermost broom handle within the tank, as shown in FIGS. 9 and 10.

In P10. 7, a finished manufactured broom or mop 107 is shown including a handle 108 comprised of a wooden stick 16' on which a polyethylene or other plastic coating 77 has been extruded. An end cap 109 is fitted over one end of the handle, the other end of the handle being secured to a broom or mop head 110.

ln operative use, the sticks 16 are fed end to end vertically through the stick feeding mechanism 29 and through the extrusion die 13. Polyethylene in a plastic softened state is injected from machine 14 into the passage 79 of the die 13. The plastic then moves into the circular space 30 around the die core 65 and is forced downward through the spaces 71 between the spacers 70 into the lower portion of the circular space 80 from where it moves down the conical space between the core and die bottom plate 73 until it comes into contact with the cylindrical surface of the stick moving downward, the plastic adhering to and directly upon the stick surface. Almost immediately thereafter, the plastic on the stick enters the water 81 in the tank which cools the plastic to shrink it tightly upon the stick. When the lower end of the handle thus formed reaches the lever platform 89, it pivots the lever causing the switch 93 to actuate an electric circuit to the solenoid. This causing air to push the ram 102 forwardly, the ram striking the bar 103 which now pivots about bolt 104. The tines 106 of the bar 103 now pushes the lowermost broom handle in an angular direction as shown in FIG. 10, thus causing the continuous plastic coat 77 to break at the junction of adjacent stick ends. The lowermost handle thus broken off floats up to the top of the tank 12 where it is manually removed while the next succeeding stick continues descending downward to the platform 89. Reverse movement of air in the pneumatic system reverses the ram direction back to its starting position, while the bar 103 pivots to its vertical position so to repeat the operational cycle.

The water cooling of the plate 53 tends to keep the wood stick from being heated to cause any moisture in the stick to expand or turn into steam and thus effect blistering of the plastic. The immediate cooling of the plastic coated stick by the tank water reduces further heating of the stick and the result is a smooth plastic coated broom handle free of blisters. The die 13 is positioned closely to the water surface in the tank and this water is continually replenished and the water surface kept as close as possible to the under extruding face of the die.

What we claim is:

1. A machine for extruding polyethylene on wood handle sticks comprising an operational unit; a water tank; said operational unit being mounted upon said water tank; a stick feeding apparatus for feeding said sticks in a vertical direction to said operational unit, said unit comprising a stick feeding mechanism, an extrusion die, said mechanism feeding said sticks through said die, and a discard mechanism for breaking off a lowermost coated handle within said water tank.

2. The combination as set forth in claim 1, wherein said stick feeding mechanism comprises a vertical tube for receiving said sticks, said tube being mounted on a plate; a pair of openings in opposite sides of said tube; a pair of rollers in said openings for engaging frictionally the opposite sides of said stick, each roller being mounted upon one of a pair of parallel shafts; a sprocket on one of said shafts; power means for driving said sprocket; each said shaft having a gear secured thereto, said gears being in engagement with each other so to transmit power from one shaft to the other; and means for moving one of said shafts toward the other said shaft so to adjustably frictionally grasp said stick between said rollers.

3. The combination as set forth in claim 2, wherein said power means comprises an endless sprocket chain engaging said sprocket and a sprocket on an output shaft of a gear reduction unit, said gear reduction unit having an input shaft carrying a pinion engaged by an endless chain engaging a second pinion on a motor shaft of an electric motor.

4. The combination as set forth in claim 3, wherein said shaft movement means comprises one of said shaft being journaled in a pair of spaced-apart bearing blocks, each said block having a horizontal groove therein; a slide block in each said groove; a bearing in each said slide block receiving the other said shaft; and a compression coil spring between each slide block and one end of said groove to normally urge said shafts in a direction toward each other to cause said rollers to frictionally engage said stick.

5. The combination as set forth in claim 4, wherein said stick feeding mechanism is spaced from said extrusion die by a heat shield therebetween, said heat shield comprising a horizontal plate with a restricted central opening for receiving said sticks therethrough; a pair of horizontal parallel passages through said plate on opposite sides of said central opening, one end of one said passage having a fitting for securement to a hose connected to a cold water source, the other end of said passage having a fitting connected to one end of a second hose which, at its opposite end, is connected to a fitting in one end of the other said passage, the other end of said other passage comprising a discharge port thus cooling the vicinity around said central opening of said heat shield.

6. The combination as set forth in claim 5, wherein said extrusion die comprises a hollow block having a cylindrical central opening; a cylindrical hollow core fixed within said opening, said core having a cylindrical sidewall with integral spacers around said side for centrally spacing said core within said cylindrical opening of said block, said core having a downwardly tapered conical wall at its lower end; a bottom plate secured to said block, said bottom plate having a conical depression on its upper side receiving therein in spaced relation said conical lower end of said core to form a space therebetween into which said polyethylene may flow; and said bottom plate having an opening therethrough in axial alignment with said conical depression, said opening being of a dimension to receive said stick and a thin film or coat of said polyethylene deposited around the side of said stick.

7. The combination as set forth in claim 6, wherein said discard mechanism comprises a vertical bar extending into said tank, said bar being secured at its upper end to a bracket mounted on said tank; a lever centrally pivotable attached to a lower end of said bar; a platform on one end of said lever for engaging a lower end of said stick, the other end of said lever being connected pivotably free to a lower end of a rod extending upwardly through an opening in said bracket, the upper end of said rod being in alignment to engage a microswitch mounted on said bracket, said switch being in electrical circuit with a solenoid connected to a piston of a first pneumatic cylinder centrally connected to an air intake hose and connected at its ends to a pair of air exhaust hoses connected at their opposite ends to opposite ends of a second cylinder having a piston connected to an exterior ram providing means for breaking off a lowermost of said polyethylene coated sticks.

8. The combination as set forth in claim 7, wherein said breaking off means comprises a bar pivotable at its upper end about a bolt in a block mounted upon said heat shield, said bar depending vertically into said tank, said bar being in alignment for engagement by said ram, and said bar having a plurality of horizontal tines in alignment to sweep against said lowermost polyethylene coated stick to break off said polyethylene film at the junction of said lowermost and an adjacent stick and thus discard said lowermost stick. 

2. The combination as set forth in claim 1, wherein said stick feeding mechanism comprises a vertical tube for receiving said sticks, said tube being mounted on a plate; a pair of openings in opposite sides of said tube; a pair of rollers in said openings for engaging frictionally the opposite sides of said stick, each roller being mounted upon one of a pair of parallel shafts; a sprocket on one of said shafts; power means for driving said sprocket; each said shaft having a gear secured thereto, said gears being in engagement with each other so to transmit power from one shaft to the other; and means for moving one of said shafts toward the other said shaft so to adjustably frictionally grasp said stick between said rollers.
 3. The combination as set forth in claim 2, wherein said power means comprises an endless sprocket chain engaging said sprocket and a sprocket on an output shaft of a gear reduction unit, said gear reduction unit having an input shaft carrying a pinion engaged by an endless chain engaging a second pinion on a motor shaft of an electric motor.
 4. The combination as set forth in claim 3, wherein said shaft movement means comprises one of said shaft being journaled in a pair of spaced-apart bearing blocks, each said block having a horizontal groove therein; a slide block in each said groove; a bearing in each said slide block receiving the other said shaft; and a compression coil spring between each slide block and one end of said groove to normally urge said shafts in a direction toward each other to cause said rollers to frictionally engage said stick.
 5. The combination as set forth in claim 4, wherein said stick feeding mechanism is spaced from said extrusion die by a heat shield therebetween, said heat shield comprising a horizontal plate with a restricted central opening for receiving said sticks therethrough; a pair of horizontal parallel passages through said plate on opposite sides of said central opening, one end of one said passage having a fitting for securement to a hose connected to a cold water source, the other end of said passage having a fitting connected to one end of a second hose which, at its opposite end, is connected to a fitting in one end of the other said passage, the other end of said other passage comprising a discharge port thus cooling the vicinity around said central opening of said heat shield.
 6. The combination as set forth in claim 5, wherein said extrusion die comprises a hollow block having a cylindrical central opening; a cylindrical hollow core fixed within said opening, said core having a cylindrical sidewall with integral spacers around said side for centrally spacing said core within said cylindrical opEning of said block, said core having a downwardly tapered conical wall at its lower end; a bottom plate secured to said block, said bottom plate having a conical depression on its upper side receiving therein in spaced relation said conical lower end of said core to form a space therebetween into which said polyethylene may flow; and said bottom plate having an opening therethrough in axial alignment with said conical depression, said opening being of a dimension to receive said stick and a thin film or coat of said polyethylene deposited around the side of said stick.
 7. The combination as set forth in claim 6, wherein said discard mechanism comprises a vertical bar extending into said tank, said bar being secured at its upper end to a bracket mounted on said tank; a lever centrally pivotable attached to a lower end of said bar; a platform on one end of said lever for engaging a lower end of said stick, the other end of said lever being connected pivotably free to a lower end of a rod extending upwardly through an opening in said bracket, the upper end of said rod being in alignment to engage a microswitch mounted on said bracket, said switch being in electrical circuit with a solenoid connected to a piston of a first pneumatic cylinder centrally connected to an air intake hose and connected at its ends to a pair of air exhaust hoses connected at their opposite ends to opposite ends of a second cylinder having a piston connected to an exterior ram providing means for breaking off a lowermost of said polyethylene coated sticks.
 8. The combination as set forth in claim 7, wherein said breaking off means comprises a bar pivotable at its upper end about a bolt in a block mounted upon said heat shield, said bar depending vertically into said tank, said bar being in alignment for engagement by said ram, and said bar having a plurality of horizontal tines in alignment to sweep against said lowermost polyethylene coated stick to break off said polyethylene film at the junction of said lowermost and an adjacent stick and thus discard said lowermost stick. 